Stock Hydraulic Lifter Preload Spec?

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mopowers

mopowers

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My dad and I are putting a mild 360 together for his D100 and need a set of pushrods. Since the heads and block have been decked and a number of other things have been changed, I'd like to measure for pushrods to see if the stockers will work or not. Do you guys happen to know what the stock spec is for hydraulic lifter preload? The lifters he's using is a stock replacement from Sealed Power (HT2011).

I've called federal mogul (sealed power), but he couldn't give me an answer, only that they're lifters are built to "factory specs" and I couldn't find the spec in the FSM.

I'm wondering if I could just measure the range of travel in the lifter and split the difference, or is there an actual recommended range?
 
My cam manufacturer recommends .080" - 0.095" for hydraulic flat tappet pre-load.

SEH4246AL.jpg
 
Mine were 080" to 095" also. They were right about 092" installed
 
typopup said:
If I remember correctly, mine were 1 1/8 turns counter-clockwise from 0 lash.
Click to expand...

1-1/8" turn on a 3/8-24 adjuster would only give you .047"; about half of what that cam card calls for. Also, I'm guessing that spec is for Hughes lifters. I need the range for factory replacement lifters. Thanks for the input though.
 
mopowers said:
1-1/8" turn on a 3/8-24 adjuster would only give you .047"; about half of what that cam card calls for. Also, I'm guessing that spec is for Hughes lifters. I need the range for factory replacement lifters. Thanks for the input though.
Click to expand...
I agree; however, taking into account the rocker ratio (1.6 for me) that gives 0.075" ... I may have been a bit off on the number of turns ... maybe it was 1 1/4 which wouldresult in ).083" lash at the valve.

The cam card states for "Standard lifter pre-load" so I guess that's a bit subjective.
 
typopup said:
I agree; however, taking into account the rocker ratio (1.6 for me) that gives 0.075" ... I may have been a bit off on the number of turns ... maybe it was 1 1/4 which wouldresult in ).083" lash at the valve.

The cam card states for "Standard lifter pre-load" so I guess that's a bit subjective.
Click to expand...
which would result in 0.083" lash (darn fat fingers)
 
mopowers said:
I'm wondering if I could just measure the range of travel in the lifter and split the difference, or is there an actual recommended range?
Click to expand...
I alwasy assumed that this is typically how the factory would set this up. But I suspect they would measure a whole kabooble of them, not just one or 2. The top position of the piston travel is predicable, but the bottom of the piston travel is not necessarily so well defined.

For performance, folks typically are going to reduce the preload. I have always assumed this is to limit the maximum amount of possible lifter pump-up if the valves DO float. So preload numbers like .030 to .040" are not uncommon. My son and I set his 340 Crane cam lifters to .050" preload.

The possible downside of less lifter preload is a longer time of them rattling at start up if they do leak down any.
 
Actually the biggest downside of running only .020 preload, on non-adjustable arms, would be what to do as the preload relaxes to zero, over the course of time.Sooner or later they will start to clatter, then it will be time for new pushrods again.
The upside of running .020 is the engine will rev till the oiling system fails, and then you have to put in new parts again.
And if the lifters do pump up no damage can be done. It just won't idle for a minute,lol
So, if you can't afford adjustable arms, and you're oiling system is stock, then Judging by how mine are holding their setting, I suspect .050 is lifetime plenty.That's an educated guess, no more than opinion.
 
If the lifters are standard replacements I'd use .050-.090 preload. If they are a performance anti-pump-up deal they get much less. Like .010-.025.
 
Thanks guys. I've typically run half to 3/4 turn on my junk with adjustable rockers, which translates to about .025". Since my dad wants to stick with non-adjustable rockers, we'll shoot for around .050-.060. The guy a federal mogul said their lifters have around .120" plunger range, so it's a pretty big window. The good thing is the machinist got all the valves within .005" on height. I appreciate the input.
 
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